1. Field of the Invention
The present invention relates to a shadow mask, and a manufacturing method thereof.
2. Discussion of the Related Art
FIGS. 1 to 3 are cross sectional views for sequentially illustrating a method of manufacturing a shadow mask according to the related art. The shadow mask is applied to a liquid crystal display apparatus (LCD apparatus) or an organic light-emitting diode (OLED) in order to form printed patterns. According to the shadow mask manufacturing method in the related art, a photoresist pattern PR is formed on a mask substrate 10 as shown in FIG. 1. The mask substrate 10 is then wet etched using the photoresist pattern PR as an etching mask as shown in FIG. 2. The photoresist pattern PR on the mask substrate 10 is finally removed as shown in FIG. 3, thereby completing the manufacturing process of the shadow mask. FIG. 4 is a plan view illustrating a part of a shadow mask according to the related art. FIG. 5 is a cross sectional view illustrating the shadow mask shown in FIG. 4, the cross sectional view taken along the line I-I′. As shown in FIG. 4 and FIG. 5, the related art shadow mask is characterized by thickness R1, size of the shadow region R2, size of the slit region R3 in which slits corresponding to final printed patterns are formed, length R4 of the upper part of the mask, and the pitch R5. Generally, the thickness R1 of a shadow mask is 40 micrometers to 50 micrometers. The size of the shadow region R2 is 100 micrometers or 120 micrometers. The size of slit region R3 is 40 micrometers, and the length R4 of upper part of the mask is about 20 micrometers.
When manufacturing the shadow mask according to the above described method, a large amount of side etching occurs beneath the photoresist pattern PR. Therefore, it is difficult to manufacture a shadow mask having slits or slots with precise sizes. Further, it is difficult to manufacture a shadow mask having slits or slots with substantially uniform sizes along the vertical direction of the mask. Generally the size of the side etching is about 40 micrometers or more when the thickness of the mask is 40 micrometers. Since it is impossible to have the pitch R5 be smaller than the sum of half the thickness of the mask (0.5*R1) and the length of the slit region R3, the pitch R5 must be 140 micrometers or more if the length of the slit region R3 is 40 micrometers. In this case, if the side etching occurs by 2 micrometers at respective sides of the slit region, the length of the slit region R3 must be 44 micrometers or more. Further, since there can be severe process errors in the shadow mask manufacturing method according to the related art, it is difficult to design a shadow mask with fine pitches or patterns using the conventional manufacturing technologies.